filter

Filter

trpc provides APIs to implement and install filter on client/server. Filter intercepts the execution of each RPC call. Users can use filter to do logging, auth, metrics collection, and other functionality that can be shared across RPCs.

Try it

go run server/main.go -conf server/trpc_go.yaml

go run client/main.go

Explanation

To make the framework more scalable, tRPC introduced the interceptor concept, which is inspired by Java's Aspect-Oriented Programming (AOP) philosophy. The specific approach is to set breakpoints before and after specified actions in the framework, and then insert a series of filters at the breakpoint locations to introduce system functions into the framework.

The ultimate goal of interceptors is to decouple business logic and system-level services, allowing for cohesive development. By presetting filter breakpoints, the program is provided with a mechanism for dynamically adding or replacing functionality to the program without modifying the source code.

Server-side

ServerFilter is the type for server-side filter.It is essentially a function type with signature: func(ctx context.Context, req interface{}, next ServerHandleFunc) (rsp interface{}, err error). An implementation of a filter can usually be divided into the breakpoints.

To install a filter for Server, configure NewServer with ServerOption server.WithFilter() or configure trpc_go.yaml with sever filter.

Client-side

Client side is similar to server side.